Determination of l-Dopa Content and Other Significant Nitrogenous Compounds in the Seeds of Seven Mucuna and Stizolobium Species in China

Abstract

Seven samples of seeds from the genera Mucuna and Stizolobium (Leguminosae) were collected throughout southern China. HPLC analysis revealed l-dopa concentrations ranging from 3.9 to 6.2%. The seeds of the most commercially available species, S. pruriens var. utilis, collected biweekly during the fruit period, were also assayed using the same method, and their l-dopa concentrations were found to vary between 4.2 to 10.6%. Other nitrogenous compounds, which are significant in chemotaxonomy between the two plant types or have potential influence on analysis of l-dopa in the seeds were identified as stizolamine 3,4-dihydro-5-hydroxymethyl-4-methyl-3-oxopyrazinyl-guanidine), l-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, and its derivatives.